Small-load runtime: overhead or automatic shutoff?

By the Ferncharge team · Figures last checked 23 October 2026

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If a small appliance stops running, record what happened before assuming the battery was too small. A runtime calculation and an output timer answer different questions.

Based on manufacturers' published pages and manuals. Ferncharge has not tested these products.

First, define what your energy figure includes

Watts describe power; watt-hours describe energy. A constant 10W load running for 10 hours uses 100Wh at the point where that load is measured. EcoFlow's explanation of watts and watt-hours provides the underlying distinction.

For an illustrative accounting model, suppose 400Wh is available at a chosen measurement boundary, a load draws 10W at that same boundary, and a separate overhead draws 5W there. Then:

Runtime = 400Wh ÷ (10W + 5W) = approximately 26.7 hours.

Ignoring the assumed overhead would give 40 hours. All three inputs are invented to show the arithmetic. They are not specifications, measured efficiency or a forecast for a named product. Real overhead and conversion losses need evidence for the actual model and output mode.

Do not count a loss twice. If your energy figure is already measured at an output socket under a comparable load, losses upstream of that socket are already reflected in the delivered energy. A battery-side figure and a socket-side load cannot simply be combined without an appropriate conversion model. State the boundary and assumptions beside the estimate.

Next, check the timer independently

EcoFlow's DELTA 2 app manual V1.0 lists separate device, screen, AC and 12V DC timeouts. Its AC timeout section describes switching off an unused output after a configured interval. A dark screen therefore does not, by itself, identify an empty battery or an inactive output. These are manufacturer-documented controls for that model and manual version, not a claim about every EcoFlow station. DELTA 2 app manual, printed page 9.

Jackery's support article describes an app-controlled main-power auto-off setting triggered by inactivity. The page does not establish which UK models support it. Check your exact model's instructions before applying that advice. Jackery auto power-off explanation.

Record enough to ask a useful question

For a non-critical appliance, follow its instructions and record:

• Station model, firmware and selected output.
• Appliance model and operating mode.
• Starting charge indication and the indication when it stopped.
• Timer settings, elapsed time and any error message.
• Whether the screen, one output or the whole station stopped.

These are Ferncharge's troubleshooting notes, not a diagnosis. An unexplained shutdown should go to manufacturer support; do not bypass protective functions or add a wasteful dummy load to defeat detection.

Decide what evidence is missing

If the station runs out of energy, seek comparable delivered-energy data. If an output stops with charge remaining, investigate settings and documented behaviour first. More nominal Wh alone does not answer the second question.

For medical or other critical loads, obtain device-specific advice and a suitable backup plan rather than relying on this illustrative calculation.

Related: Why does a power station switch off with a small device? · Why it runs out faster than expected · Power station runtime calculator · Spec table